R package for geocoding and local photon setup

[JsLth]

I developed a local photon setup manager for another project and thought it would be nice in a package. Unfortunately, the previous photon R package was abandoned a while ago, so I made my own: https://github.com/JsLth/photon

The package is now on CRAN and implements the basic geocode, reverse and structured endpoints. Additionally, it features a class photon_local, which allows to programmatically download necessary files, start, stop and manage setup errors. It's designed to be used in reproducible projects (e.g. for a paper or a report) without having to fiddle with system commands and file downloads manually. It also uses timestamps for the search indices to make it easier to keep track of what time the extracts were created.